President Barack Obama's convention evolution complete

Eight years ago, the little-known Democrat rocketed into the political spotlight with a soaring convention keynote address. Four years later, he accepted the Democratic Party's nomination and became its standard bearer.

On Thursday and now the president, Obama took the stage fighting for his job.

"I recognize that times have changed since I first spoke to this convention," Obama said. "The times have changed, and so have I."

"I'm no longer just a candidate. I'm the president," he said, drawing cheers from the crowd of 15,000.

It was a telling transformation for Obama, locked in a tight re-election battle with Republican Mitt Romney. After taking office with sky-high hopes in 2008, Obama now is hampered by a shaky economy and dampened enthusiasm among his supporters.

His prime-time convention speech, delivered two months from Election Day, was meant to set the tone for the campaign's final stretch.

So, with thousands in the audience and millions watching from elsewhere, the president asked for more time. Obama urged voters to stay patient even though his economic policies have failed to fully fix the American economy. Once the candidate of hope, Obama's message was hang in there.

"America, I never said this journey would be easy, and I won't promise that now," he said, "Yes, our path is harder -- but it leads to a better place. Yes our road is longer, but we travel it together."

In 2008, Obama ran for office on a platform of lofty ideas, many of which have gone unfulfilled during his years in the White House. This time around, Obama acknowledged that the campaign sometimes seems small, even silly.

"Trivial things become big distractions. Serious issues become sound bites," he said. "And the truth gets buried under an avalanche of money and advertising."

Obama never mentioned his own role in the 2012 campaign's increasingly nasty tone. The president's campaign has hammered Romney, a successful businessman, as a corporate raider who sought profits at all cost. A Democratic super PAC supporting Obama ran an ad linking him to the cancer death of a man who worked for a company Romney's private equity firm controlled. And the president never asked his allies to take it down, despite questions about its accuracy.

On this night, gone was the excitement of someone new that was felt during his two previous convention appearances. And Obama, the graying incumbent, didn't try to recreate it.

Instead, he whittled the election down to a choice, spelling out his vision of how to create economic opportunity for all, and warning that Romney would restore trickle-down ideas that Obama says were quietly gutting the economy for years before crashing it completely.

The president offered a rousing defense of good government and how Democrats see the world. He made a case for citizenship over cynicism, part of a broad appeal to independent voters who want Washington to work better but loathe its growing cost at their expense.

"We insist on personal responsibility and we celebrate individual initiative. We're not entitled to success," Obama said. But he added: "We don't think government can solve all our problems. But we don't think that government is the source of all our problems."

Gone, too, was the setting Obama wanted for the biggest address of his re-election bid.

Democrats opted for their convention's rented basketball arena instead of a much larger, open-air football stadium for Obama, wary of the safety and political risks if rain came pouring down.

"We can't let a little thunder and lightning get us down. We're going to have to roll with it," Obama said in a phone call earlier Thursday to supporters who lost their chance to attend because of the site switch.

In a nation in which more than 23 million people are unemployed or underemployed, Obama focused on the millions who have found work, and how many more can, too. He talked of education and energy and innovation and job training.

He had help making his case this week.

As former President Bill Clinton put it on Wednesday: "No president -- not me, not any of my predecessors -- no one could have fully repaired all the damage that he found in just four years. But he has laid the foundations for a new, modern, successful economy of shared prosperity. And if you will renew the president's contract, you will feel it."

Obama walked off stage after 11 p.m. with wife Michelle and daughters Malia and Sasha by his side.

The next time he steps on the convention stage will be as an outgoing president or as an ex-president.